Implantable cardiac rhythm management devices are widely used in medicine. Some illustrative devices include implantable cardiac monitors, such as an implantable loop recorder, implantable pacemakers, implantable defibrillators, and implantable cardiac resynchronization systems.
Some implantable cardiac rhythm management devices are configured to sense cardiac activity of a patient and detect individual cardiac cycles or “beats” of the patient. To perform such sensing, systems sometimes make use of a detection profile. Some examples of detection profiles are shown in U.S. Pat. No. 5,709,215 to Perttu et al. and U.S. Published Patent Application No. 2009-0228057, titled ACCURATE CARDIAC EVENT DETECTION IN AN IMPLANTABLE CARDIAC STIMULUS DEVICE, the disclosures of which are incorporated herein by reference.
There are numerous ways that such systems and sensing methods can encounter difficulties. Underdetection or dropout, where a cardiac cycle goes uncounted, and overdetection, where a cardiac cycle is counted more than once, are two examples. Misdetection, where a cardiac cycle is counted but not in the manner planned, is another example. Noise detection, where a signal that is non-cardiac is counted, is yet another example. All of these are types of malsensing. Alternatives and new enhancements that reduce malsensing are desired.